Method of printing with a heat settable ink



' ME'rnonoF PRINTING WITH A HEAT 7 SETT-ABLE INK 7 "George W. Reinke,'lalos Verdes Estates, Calif, assignor to Rineglas, line, a corporation of'lllinoisj No Drawing. Filed June 25, 1962, Ser. No. 205,072 3 Claims. (Cl. 101-429) Thisinvention relates in :general to a heat settable or curable ink and method, of drying or curing same, and

more particularly to. a method of printing and curing of a film of ink imprinted onto a backing or supporting member. Still more particularly, the invention relates to the method of printing and curing a film of the ink imprinted onto a supporting surface or backing member, including quickly drying or curing the imprinted ink, and imparting a finish to the external ink surface, wherein the cured film thickness is substantially the same as the wet film thickness. l

The inkof the present invention is useful in the printing industry, wherein it is to be imprinted on any suitable ink-receptive material, such, as paper, paperboard, fabric and metal, and wherein extremely rapid drying or curing of the ink is effected bymomentary application of heat directly to the ink. More particularlygthe ink of the present invention-is especiallyuseful in silk screen printing applications, wherein the ink is applied inany thickness desired, such as from one-half a mil to in excess'of one mil. Since the ink of the present invention is of a type that substantially does not change in volume between the wet and curedstate, when a one-half mil film or thickness of ink is applied to a backing sheet in wet form, the entire ink thickness will remain substantially the same after the ink is cured. While the conventional ink of the prior art, having a substantial amount of solvents needed for drying, would require a deposit of .001 to .0018 inch thick when wetto produce a dry or cured thickness of .0006 inch. Thus, the hiding power (opacity) of the ink of the present invention is high and it is therefore in the first instance.

Inasmuch as the ink of the present invention would include very little if any solvent, it is especially suitable for silk screen printing since it will not dry on the screen, and this feature eliminates the necessity of much screen maintenance. Moreover, the finish on the ink surface of the instant ink may be varied in accordance with the method of curing as will be hereinafter explained, without necessitating the changing of the ink supply as was heretofore required.

The'heat curable or settable ink of the present inventionis a plastisol mixture of finely divided particles of vinyl resin, along with pigment particles, in suspension in plasticizer materials. cludes a plasticizer, a monomer, a catalyst for the monomer, a polyvinyl resin and a pigment, which mixture will set up or cure only upon being subjected to a predeter- More particularly, the mixture in-- Ice Catalyst: 4/ 10 part'by weight benz'oyl peroxide Polyvinyl resin: 80 parts by weight high molecular weight polyvinyl chloride resin (Geon 121 resin, B. F.'Goodrich) t Pigmentr 30 parts by weight titanium dioxide The above ink example will setup partially at betweeh 20022 5 F., and fully at between BOO-325 F. In some instances of the printing oftheink, it is not necessary to completely cure the ink, but where maximum durability is desired, a. complete curing of ink: is necessary. It should be further appreciated that the-ink curing temperature depends upon the formulationof the ink. Moreover, the formulation may be adjusted to varythe resulting rigidity of the cured ink, and/or other characteristics;

The methodof curing a film of the inkwhen applied to a backing sheet or Web, such as when printing-on a sheet or web of paper, involves the direct application of a sufficient amount of heat to the external surface of the ink to effect setting or curing thereof. Application of heat against the externalsurface of the ink may be carried I out'by directly engaging the external surface of the ink with a suitable heated element such as a plate, roller or belt. For example, a sheet having wet ink-imprinted thereon may be carried against or around a heated hollow drum or roller, or against a heated belt with the external surface of the ink in direct engagement with the roller or belt surface. The linear'speed of the sheet, would be the same as that of the roller or belt surface. Similarly, a heated plate may be applied against the externalsurface of the ink for the curing operation where the sheet would be stationary. Thus the heat is applied directly to the ink for drying or curing of the ink. The sheet imprinted with the ink will have greater ink adhering characteristics than the roller, belt or plate surface in order to prevent 7 transfer of the ink to the roller, belt or plate.

V vention, without having to apply an extremely heavy film Itshould be appreciated that only momentary contact would be established between a moving sheet or web of material and arotating drum or roller or moving belt,

in which case the roller, drum or belt would be heated to A desired finish on the external surface of the ink is obtained by a combination of pressure, heat, and the heated element surface. -Where the heatedelement' and imprinted sheet material are moving, the heat and pressure components will vary with the speed and type of paper or supporting surface being printed. For example, the pressure should be such as to give the proper finish but not to be excessive as to move or spread the print on the'paper. If a smooth, glossy finish is desired on the cured ink surface, a polished roller, belt or plate may be employed. More particularly, the roller may have a highly polished chrome surface. On the other hand, if a textured pattern is desired on the cured ink surface for the ink finish, a textured roller may be employed. For example, a dull ink finish may be accomplished by using I a roller having a Teflon surface. ,Other finishes may be mined amount .of heat; 'It should be appreciated that Plasticizer: 20 par-ts by weight dioctyl phthalate Monomer: 20 parts by weight high boiling low viscosity monomeric ester (experimental monomer X970, Rohm & Haas) (X970 is a 1,3 butylene glycol di-methacrylate) provided with rubber-surfaced rollers. Accordingly, variousink finishes maybe provided with the same basic ink and by merely changing the roller surface.

The present invention of having a heat settable or curable ink and a method of s'etting'the-ink by use of a roller.

or the like materially speeds up1printing operations especially in the silk screen printing art, and now allows use of high speed printing equipment. For example, the ink may be dried or cured by passing the imprinted sheet material over a heated roller or suitable element with the ink directly in engagement with the heated element, and

thereby permit drying or curing times as short as approximately one-half a second. Such short drying or curing times permits immediate stacking of printed sheets, and

immediate further printing of other colors or other designs, such as where presses may be arranged in tandem for several printing operations. In fact, by applying heat only to the ink, the supporting surface of the ink such as paper would not even be heated. And the ink, when imprinted on a backing sheet, being liquid and wet and in intimate contact with a heated element, conducts the heat more rapidly to hasten the curing process. Moreover, because the volume or film thickness of the ink of the present invention does not change to any degree, savings in ink may be realized over using inks with solvents.

The method of curing is described herein in connection with one type of plastisol mixture that may be defined as a mixture having a one hundred percent solids in that film thickness, wet and cured, remain the same, but the method may well be employed with other plastisol mixtures having ninety to one hundred percent solids. Moreover, the ink drying or curing method of this invention may be applied to other heat settable resins.

It will be understood that modifications and variations may be eflFected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. The method of printing a heat settable ink containing 90 to 100 percent solids onto an ink receptive material comprising the steps of, applying wet heat settable ink to one surface of the ink receptive material through a silk screen to provide imprinting thereon, moving the material with the wet ink thereon into engagement and under slight pressure with aheated surface of a movable element moving at the same speed as said material so that the heated surface of said element directly engages the exposed surface of the wet ink, and allowing the moving element to be in momentary engagement with the wet ink to increase the ink temperature to between 200 and 325 F. for a. time sufficient to set the ink without heating said material and to impart to the exposed surface of the ink a finish in accordance with the finish of the heated surface of the element, wherein the set ink thickness is substantially the same as the wet ink thickness.

2. The method of claim 1, wherein the surface of the heated element is highly polished, and thereby application of a glossy surface to the set ink is accomplished.

3. The method of claim 1, wherein the surface of the heated element is textured, and thereby application of a textured surface to the set ink is accomplished.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD OF PRINTING A HEAT SETTABLE INK CONTAINING 90 TO 100 PERCENT SOLIDS ONTO AN INK RECEPTIVE MATERIAL COMPRISING THE STEPS OF, APPLYING WET HEAT SETTABLE INK TO ONE SURFACE OF THE INK RECEPTIVE AMTERIAL THROUGH A SILK SCREEN TO PROVIDE IMPRINTING THEREON, MOVING THE MATERIAL WITH THE WET INK THEREON INTO ENGAGEMENT AND UNDER SLIGHT PRESSURE WITH A HEATED SURFACE OF A MOVABLE ELEMENT MOVING AT THE SAME SPEED AS SAID MATERIAL SO THAT THE HEATED SURFACE OF SAID ELEMENT DIRECTLY ENGAGES THE EXPOSED SURFACE OF THE WET INK, AND ALLOWING THE MOVING ELEMENT TO BE IN MOMENTARY ENGAGEMENT WITH THE WET INK TO INCREASE THE INK TEMPERATURE TO BETWEEN 200 AND 325*F. FOR A TIME SUFFICIENT TO SET THE INK WITHOUT HEATING SAID MATERIAL AND TO IMPART TO THE EXPOSES SURFACE OF THE INK A FINISH IN ACCORDANCE WITH THE FINISH OF THE HEATED SURFACE OF THE ELEMENT, WHEREIN THE SET INK THICKNESS IS SUBSTANTIALLY THE SME AS THE WET INK THICKNESS. 